1. Field of the Invention
This invention relates generally to communication connectors, and particularly to a connector assembly that compensates for crosstalk among different signal paths conducted through the assembly.
2. Discussion of the Known Art
There is a need for a durable, high frequency communication connector assembly that compensates for (i.e., cancels or reduces) crosstalk among and between different signal paths within the assembly. As broadly defined herein, crosstalk occurs when signals conducted over a first signal path, e.g., a pair of terminal contact wires associated with a communication connector, are partly transferred by inductive or capacitive coupling into a second signal path, e.g., another pair of terminal contact wires in the same connector. The transferred signals define "crosstalk" in the second signal path, and such crosstalk degrades any signals that are routed over the second path.
For example, an industry type RJ-45 communication connector has four pairs of terminal wires defining four different signal paths. In typical RJ-45 plug and jack connectors, all four pairs of terminal wires extend closely parallel to one another over the lengths of the connector bodies. Thus, signal crosstalk may be induced between and among different pairs of terminal wires within the typical RJ-45 plug and jack connectors, particularly when the connectors are in a mated configuration. The amplitude of the crosstalk becomes stronger as the coupled signal frequencies or data rates increase.
Applicable industry standards for rating the degree to which communication connectors exhibit crosstalk, do so in terms of so-called near end crosstalk or "NEXT". Moreover, NEXT ratings are typically specified for mated connector configurations, e.g., a type RJ-45 plug and jack combination, wherein the input terminals of the plug connector are used as a reference plane. Communication links using unshielded twisted pairs (UTP) of copper wire are now expected to support data rates up to not only 100 MHz, or industry standard "Category 5" performance; but to meet "Category 6" performance levels which call for at least 46 dB crosstalk isolation at 250 MHz.
U.S. Pat. No. 5,186,647 to Denkmann et al. (Feb. 16, 1993), which is assigned to the assignee of the present invention and application, discloses an electrical connector for conducting high frequency signals. The connector has a pair of metallic lead frames mounted flush with a dielectric spring block, with connector terminals formed at opposite ends of the lead frames. The lead frames themselves include flat elongated conductors each of which includes a spring terminal contact wire at one end for contacting a corresponding terminal wire of a mating connector, and an insulation displacing connector terminal at the other end for connection with an outside insulated wire lead. The lead frames are placed over one another on the spring block, and three conductors of one lead frame have cross-over sections configured to overlap corresponding cross-over sections formed in three conductors of the other lead frame. All relevant portions of the mentioned '647 patent are incorporated by reference herein. U.S. Pat. No. 5,580,270 (Dec. 3, 1996) also discloses an electrical plug connector having crossed pairs of contact strips.
Crosstalk compensation circuitry may also be provided on or within layers of a printed wire board, to which spring terminal contact wires of a communication jack are connected within the jack housing. See U.S. patent application Ser. No. 08/923,741 filed Sep. 29, 1997, and assigned to the assignee of the present application and invention. All relevant portions of the '741 application are incorporated by reference herein. See also U.S. Pat. No. 5,299,956 (Apr. 5, 1994).
U.S. patent application Ser. No. 09/264,506 filed Mar. 8, 1999, and assigned to the assignee of the present application and invention, discloses a communications connector assembly having co-planar terminal contact wires, wherein certain pairs of the contact wires have opposed cross-over sections to provide inductive crosstalk compensation. All relevant portions of the '506 application are also incorporated by reference herein.
Further, U.S. Pat. No. 5,547,405 (Aug. 20, 1996) discloses an electrical connector having signal carrying contacts that are stamped as lead frames from a metal sheet. Certain contacts have integral lateral extensions that overlie enlarged adjacent portions of other contacts to provide capacitive coupling crosstalk compensation. A dielectric spacer is disposed between an extension of one contact and an enlarged adjacent portion of the other contact. Thus, the stamped lead frames for the connector of the '405 patent are complex, and are relatively difficult to manufacture and assemble precisely.
There remains a need for a communication jack connector assembly which, when mated with a typical RJ-45 plug, provides both inductive and capacitive crosstalk compensation such that the mated connectors will meet or surpass Category 6 performance.